A sheet processing apparatus configured to process sheets such as marketable securities includes a sheet take out apparatus, an inspection device, and a sorting apparatus (see Japanese Patent Application Publication No. 2007-182318, for example). The sheet take out apparatus is configured to take out sheets one by one from sheets collectively set. The inspection device is configured to convey and inspect the sheets taken out by the sheet take out apparatus. The sorting apparatus is configured to sort the sheets based on the inspection result made by the inspection device.
The inspection device determines a type of sheet (hereinafter referred to as a sheet type), a conveyance state of the sheet, an authenticity of the sheet, and a negotiability of the sheet. In the determination of the authenticity, the inspection device determines whether the sheet is an authentic sheet or an inauthentic sheet. In the determination of the negotiability, the inspection device determines whether the sheet is a negotiable sheet or a nonnegotiable sheet. The sorting apparatus includes a stacking device and a banding device. The stacking device stacks the sheets sorted based on the determination result made by the inspection device. The banding device bands each predetermined number of sheets by a paper band after the sheets are stacked in the stacking device.
The sheet take out apparatus includes a supply table on which sheets are stacked; a chamber having an air hole; a take out rotor which has a suction hole and rotates around the outer circumference of the chamber; a separation roller; and multiple conveyor rollers and multiple conveyor belts which convey the taken-out sheets. The chamber is fixed in a predetermined position and the air hole is also fixed in a predetermined position (see, for example, Japanese Patent Application Publication No. 2001-171854). A vacuum pump is connected to the chamber, thereby being capable of attracting a sheet through the air hole of the chamber and the suction hole of the take out rotor. Along with every rotation of the take out rotor, a top sheet is attracted to the suction hole and is taken out accordingly. The separation roller has a suction hole on a side facing the take out rotor. The separation roller rotates in a reverse direction to the rotational direction of the take out rotor. When the take out rotor takes out two sheets overlapping each other, the separation roller separates the second sheet from the first sheet by attracting the second sheet. Thus, the separation roller prevents two sheets from being taken out at the same time.
As far as sheets each have an entirely uniform thickness, a top surface of the sheets stacked on the supply table is not inclined. Thus, the top sheet stably comes into contact with the take out rotor and is stably attracted through the suction hole of the take out rotor. However, when sheets each have a partially uneven thickness, or specifically, when the sheets each have a larger thickness in a rear part in a sheet take out direction than in the other part, the top surface of the stacked sheets is inclined with respect to the horizontal plane because a rear end of the top surface is elevated.
In this case, the take out rotor does not stably come into contact with a take-out-side end portion of the top sheet. Thus, the top sheet is likely to fail to be taken out without being attracted to the take out roller through the suction hole of the take out roller. Accordingly, no sheet is taken out until the take out rotor makes another rotation. This makes a take-out pitch longer, and thus deteriorates a take out processing rate. Moreover, if the take out rotor repeatedly fails to come into contact with sheets, it is determined that the sheets cannot be taken out. Consequently, the operation of the apparatus is stopped.